1. Field of the Invention
The present invention relates to a system for fuming an object suspected of containing latent fingerprints thereon with cyanoacrylate vapors and an emissive metal complex. More particularly, the invention relates to developing a latent fingerprint by heating a cartridge which contains both of the following elements on a heat resistant support: 1) a polycyanoacrylate, and 2) a volatile, emissive lanthanide metal-complex or actinide metal-complex. Application of heat to the cartridge results in the production of emissive cyanoacrylate vapors. This invention also pertains to the use of a class of volatile, emissive metal-complexes that are particularly useful in the enhancement and visualization of latent fingerprints.
2. Background of the Art
Various methods have been described for the enhancement and subsequent visualization of fingerprints. Many of these techniques are discussed in chapters 3, 4, and 5 of Henry C. Lee and R. E. Gaensslen Advances in Fingerprint Technology, Elsevier, New York, 1991. One of the best methods for developing latent prints is to expose the article, suspected of containing the prints, to cyanoacrylate vapors. The vapors are preferentially deposited onto the fingerprint residue. It is generally believed that various components in the fingerprint residue cause the cyanoacrylate to undergo a polymerization reaction whereby an enhanced fingerprint image results.
U.S. Pat. No. 4,504,408 entitled "Fluorescent Vapor Fumes For Use With A Self-Contained Fingerprinting Kit" and U.S. Pat. No. 4,613,515 entitled "Fingerprint Development Kit and Process" describe methods of enhancing and visualizing fingerprints. In U.S. Pat. No. 4,504,408, fluorescent cyanoacrylate vapors are generated by allowing a liquid monomeric cyanoacrylate to contact an activator pad previously impregnated with a fluorescent compound and a composition which contains two components A and B. A is a mixture of chloroethane and methanol and B contains a polymerization catalyst in a mixture of the following solvents: nitromethane and/or nitroethane, methanol, toluene. An alternative construction involved adding the cyanoacrylate and the fluorescent dye to a gauze pad which had been treated with the two component composition A and B referred to above. Both these processes involve the transfer of liquid(s) and the release of several volatile organic compounds, in addition to producing the desired fluorescent cyanoacrylate fumes. As a result, that kit requires that the process be carried out in an enclosed area or preferably in an enclosed chamber. Also, once the liquid cyanoacrylate has been added, vapors are generated until the reaction has run its course, presumably when one of the reagents (i.e., the monomeric cyanoacrylate or the catalyst) is either consumed or otherwise neutralized, or when the heat generated is unable to sustain the production of the fluorescent cyanoacrylate vapors. No simple means of terminating the process once it has been started is given in this patent. In U.S. Pat. No. 4,613,515 a kit is also described. This kit is comprised of the following: 1) a container of a liquid cyanoacrylate monomer or polymer precursor and a polymerization inhibitor, 2) a separate container containing an inert pad having sorbed therewith at least one catalyst for the polymerization of a monomeric cyanoacrylate ester or polymer precursor, and a fingerprint development enhancer. The preferred pad material is either cotton or flax. Upon addition of the cyanoacrylate monomer to the pad, a reaction ensues, producing cyanoacrylate vapors and in some constructions fluorescent vapors. The pad is intended for a one time use. As in the previous kit, the reaction, once initiated, is allowed to proceed until either one of the reagents is exhausted or the heat generated by the reaction is insufficient to generate fluorescent cyanoacrylate vapors.
Other systems utilizing cyanoacrylate vapors have also been disclosed. WO 8801616-A teaches the use of solid Dieis-Alder adducts of cyanoacrylate as monomeric cyanoacrylate precursors. When these adducts are heated, the adducts undergo a retro-Diels-Alder reaction whereby monomeric cyanoacrylate derivatives are generated. Some of the cyanoacrylate derivatives have covalently attached fluorescent dyes. This system has the advantage of using a solid composition. However, the high molecular weight of some of the compositions and the resultant low vapor pressure of these fluorescent cyanoacrylate monomers limit the effectiveness of this approach. Other shortcomings of this system are discussed in a dissertation entitled "Detection Of Latent Fingerprints With Cyanoacrylates: New Techniques Involving Coloured And Photoluminescent Compounds" by Siaw-Jan Yong, The Australian National University, GPO Box 4, Canberra, ACT 2601 on pages 64-81. The above dissertation also discusses a device and a method for the volatilization of polycyanoacrylates. This apparatus consists of a glass chamber equipped with a controllable electric heating element attached to a heat conducting holder. The article suspected of having a fingerprint is suspended in the chamber by a wire. The heat conducting holder is charged with monomeric or polymeric cyanoacrylate and the heating element turned on. This device provides an excellent means of controlling the rate of vaporization. However, for field work it is somewhat cumbersome and requires an electric power source. A modified apparatus for the co-volatilization of cyanoacrylates and fluorescent compounds is also described. This apparatus is similar to the one previously described but contains a second, separate heating element. The co-volatilization experiments were accomplished by placing the cyanoacrylate on one holder and the fluorescent compound on the other holder, and then heating the two holders to separate temperatures to provide vapors of both species.
Other methods for visualizing fingerprints involve staining or dusting cyanoacrylate developed prints with a fluorescent dye or pigment or, alternatively, exposing cyanoacrylate developed prints to fluorescent dye vapors. These methods are discussed in the following references: J. Almog and A. Gabay, Journal of Forensic Science, 25, 1980, 408-409; J. Almog et. al., Journal of Forensic Science, 32, 1987, 585-596; E. R. Menzel, Journal of Forensic Science, 27, 1982, 918-922. E. R. Menzel et. al., Journal of Forensic Science, 28, 1983, 307-317; J. A. Butt and E. R. Menzel, Journal of Forensic Science, 30, 1988, 364-370; C. A. Pounds and R. R. Grigg, Journal of Forensic Science, 35, 1980, 169-175; H. K. Korbus, R. N. Warrener, and M. Stoilovic, Forensic Science Internation, 23, 1983, 233-240.
Post-treatment of cyanoacrylate fingerprints by pigments or stains has been disclosed in the following patents or patent applications: Japanese Patents: J02268744A and J6316194OA; U.S. Pat. Nos. 4,917,987, 4,794,260, and 4,708,882.
Various acrylate constructions containing fluorescent agents have been described. U.S. Pat. No. 3,322,680 relates to polymeric compositions containing a bis(benzoxazolyl) fluorescent agent. These compositions can be in the form of films, fibers, filaments, sheets, and other shaped objects. Although there are no specific references to cyanoacrylates, acrylates generally are described. U.S. Pat. No. 4,751,020 discloses UV-fluorescent cyanoacrylate adhesive compositions. The fluorescent agent is selected from either specific bis(benzoxazolyl) derivatives or specific coumarin derivatives. The composition may contain standard additives, such as polymerization inhibitors, thickeners, plastizers, perfumes, dyes, pigments, and polymerization catalysts.
In a copending patent application, U.S. Ser. No. 08/059,063, filed May 11, 1993 and bearing attorney's Docket No. FN 49571USA8A, several classes of organic compounds are identified which, when covolatilized with monomeric or polymeric cyanoacrylates, are useful in the enhancement of latent fingerprints. In general, these materials have molecular weights in the range of 100 to 500 Daltons and have fluorescent quantum yields greater than 10.sup.-4.